Electronic thermostat

ABSTRACT

The present invention relates generally to an electronic thermostat. More particularly, the present invention relates to an electronic thermostat configured to operate a valve by using expansion pressure of a thermally expandable material as a heater generates heat, wherein foreign substances are prevented from being accumulated in a guide cap, thus preventing malfunction of the valve from occurring. The electronic thermostat configured to control flow of a coolant by using a piston reciprocating in response to expansion and contraction of a thermally expandable material includes: a casing; a heater; a guide; the piston; a sealing member; a guide cap; and a valve, wherein the guide cap has a discharge hole formed at a lower end thereof.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to an electronic thermostat. More particularly, the present invention relates to an electronic thermostat configured to operate a valve by using expansion pressure of a thermally expandable material as a heater generates heat, wherein foreign substances are prevented from being accumulated in a guide cap, thus preventing malfunction of the valve from occurring.

Description of the Related Art

As well known in the art, a thermostat for a vehicle is mounted between an engine and a radiator, and has a valve that is automatically opened and closed in response to a temperature change of a coolant to control the flow of the coolant to the radiator and thus to maintain the coolant temperature within a desired range. In other words, the thermostat controls the flow of the coolant in accordance with opened and closed positions of the valve, thus controlling the engine temperature.

Meanwhile, the thermostat for the vehicle is based on a mechanical thermostat having a structure in which an expansion force of a thermally expandable material such as wax expandable according to the coolant temperature is transferred to a piston to cause the valve to be movable between an opened position and a closed position. Typically, such a mechanical thermostat includes a frame mounted on a passage of the coolant, a valve opening and closing the passage of the coolant, a spring biasing the valve to the closed position, and a capsule including the thermally expandable material and the piston. As the coolant temperature increases to a specified temperature (approximately 80 to 90° C.), the thermally expandable material transitions from a solid state to a liquid state, and the expansion force generated by the volume change is transferred to the piston to move the valve.

The mechanical thermostat thus constructed is operable in response to an opening/closing temperature set to the specified temperature of the coolant. In other words, the mechanical thermostat simply allows the valve to be opened and closed at a predetermined temperature and thus cannot actively cope with demand for high performance/high efficiency vehicles and changes in driving environment or conditions. To compensate for the drawbacks of such a mechanical thermostat, an electric thermostat based on a variable control system capable of maintaining the temperature of an engine coolant within an optimum range has been developed.

Herein, a typical electronic thermostat further includes a connector for power supply and a heater for reacting the thermally expandable material in addition to basic components of a typical mechanical thermostat. In this case, a separate heat source generated upon application of electric power is used to control the quantity of heat of the heater in accordance with driving environments of a vehicle such as driving speed, temperature of intake air, engine load, and the like, thus variably controlling valve opening/closing timing.

However, the above-described electronic thermostat in the related art is problematic in that after long-term use, foreign substances, which are present in a cooling system of a vehicle engine, enter a water temperature control assembly (WTCA) when the engine is stopped and are gradually accumulated in a guide cap moving upward and downward in response to upward and downward movement of the piston, leading to malfunction of the valve which occurs when the valve is kept in an opened state due to the accumulated foreign substances.

The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.

[Documents of Related Art] Korean Patent No. 10-1205014

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problem occurring in the related art, and an objective of the present invention is to provide an electronic thermostat capable of preventing foreign substances from accumulating by provision of a discharge hole formed in a guide cap and thus preventing malfunction of a valve from occurring.

Another objective of the present invention is to provide an electronic thermostat capable of preventing foreign substances accumulated in the guide cap from flowing between a piston and a guide and thus preventing malfunction from occurring due to inflow of the foreign substances.

Still another objective of the present invention is to provide an electronic thermostat, wherein a ring-shaped member is provided at an upper portion of the guide cap such that foreign substances are prevented from penetrating into the guide cap from thereabove while hot water flowing through the discharge hole is prevented from being discharged to the upper portion of the guide cap.

In order to achieve the above objectives, according to one aspect of the present invention, there is provided an electronic thermostat configured to control flow of a coolant by using a piston reciprocating in response to expansion and contraction of a thermally expandable material, the electronic thermostat including: a casing having a space defined therein to accommodate the thermally expandable material; a heater inserted into the thermally expandable material filled in the space of the casing and generating heat upon application of an external power source; a guide provided at a lower portion of the casing and bearing an expansion pressure of the thermally expandable material that expands; the piston provided to be movable upward and downward along an inner peripheral surface of the guide; a sealing member provided at a lower end portion of the casing and sealing the thermally expandable material in the casing; a guide cap provided to be movable upward and downward on a passage of the coolant along an outer peripheral surface of the guide by a pressing force exerted thereon by the piston; and a valve coupled to the guide cap to open and close the passage, wherein the guide cap has a discharge hole formed at a lower end thereof.

The electronic thermostat may further include a ring-shaped member provided between the guide cap and the guide.

Herein, the guide may have a cylindrical seal cap mounted to a lower end thereof.

Furthermore, the seal cap may include: a sealing portion being in surface contact with an outer peripheral surface of the piston; and a coupling portion coupled to the lower end of the guide, wherein the coupling portion may have a groove structure centrally formed on an inner peripheral surface of the seal cap, and the guide may have a protrusion formed at the lower end thereof to correspond to the groove structure.

Meanwhile, the groove structure and the protrusion may be configured such that an inner diameter and an outer diameter thereof increase upward, respectively.

The present invention provides the discharge hole formed in the lower portion of the guide cap such that foreign substances such as sand generated during the engine injection molding process are prevented from being accumulated in the guide cap, thus preventing malfunction of the valve from occurring when the valve is kept in the opened state due to the accumulated foreign substances.

Furthermore, the present invention provides the seal cap mounted to the lower end of the guide, thus preventing foreign substances accumulated in the guide cap from penetrating between the piston and the guide before being discharged through the discharge hole.

Furthermore, the present invention provides the ring-shaped member mounted to the upper portion of the guide cap to be in contact with the guide, thus preventing foreign substances from flowing into the guide cap from thereabove.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a vertical sectional view showing an electronic thermostat according to an embodiment of the present invention;

FIGS. 2A and 2B are views showing a seal cap of the electronic thermostat according to the embodiment of the present invention;

FIGS. 3A and 3B are views showing a guide of the electronic thermostat according to the embodiment of the present invention;

FIGS. 4A and 4B are views showing a guide cap of the electronic thermostat according to the embodiment of the present invention; and

FIG. 5 is a vertical sectional view showing an opened state of a valve of the electronic thermostat according to the embodiment of the present invention.

EXPLANATION OF REFERENCE NUMERALS

-   100: casing -   200: heater -   300: guide -   400: piston -   500: sealing member -   600: guide cap -   700: valve

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is provided as illustrative examples only to describe structural and functional features of the present disclosure, and thus the present disclosure is not to be construed as being limited by the examples described herein. That is, the present invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments that may be included within the spirit and scope of the present invention as defined by the appended claims.

Meanwhile, the terms described in the present application should be understood as follows.

Terms such as “a(the) first” and “a(the) second” may be used for explaining various constitutive elements, but the constitutive elements should not be limited to these terms. These terms are used only for the purpose for distinguishing a constitutive element from other constitutive element. For example, a first constitutive element may be referred as a second constitutive element, and the second constitutive element may be also referred to as the first constitutive element.

It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion such as “between” versus “directly between”, “adjacent” versus “directly adjacent”, etc.

As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise”, “include”, “have”, etc. when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or combinations of them but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or combinations thereof.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

FIG. 1 is a vertical sectional view showing an electronic thermostat according to an embodiment of the present invention, FIGS. 2A and 2B are views showing a seal cap 310 of the electronic thermostat according to the embodiment of the present invention, FIGS. 3A and 3B are views showing a guide 300 of the electronic thermostat according to the embodiment of the present invention, and FIGS. 4A and 4B are views showing a guide cap 600 of the electronic thermostat according to the embodiment of the present invention. The electronic thermostat according to the present invention may include a casing 100, a heater 200, a guide 300, a piston 400, a sealing member 500, a guide cap 600, and a valve 700.

The casing 100 has a space defined therein for accommodating a thermally expandable material, for example, a wax, and the thermally expandable material is filled in the space. Herein, the casing 100 is structured such that the heater 200 is coupled to an upper portion thereof, causing the heater 200 to be maintained in a state of being inserted in the thermally expandable material.

The heater 200 is connected to an external power source through a connector 1100, and is configured such that a coil (not shown) provided therein generates heat when the external power source is applied through the connector 1100. Herein, the heater 200 has an end inserted into the thermally expandable material in the casing 100 and causes the temperature of the thermally expandable material to increase by using heat generated from the coil.

Furthermore, the heater 200 may include a pair of lead wires 210 to be connected to the external power source through the connector 1100. Herein, the pair of lead wires 210 is also connected to the coil provided in the heater 200. Herein, a bushing 1200 is constructed from an insulating material and performs an insulating function to prevent formation of an electric contact between the metal casing 100 and the lead wires 210 while holding the shape of the lead wires 210. The bushing 1200 is configured to seal the inside of the casing 100 and secure the respective lead wires 210 passing therethrough, preventing the respective lead wires 210 from being broken or bent in the casing 100 and thus brought into contact with the casing 100 due to an impact energy involving vibrations generated during running of a vehicle while providing a stable connection between the lead wires and the connector 1100.

Meanwhile, the guide 300 is provided at a lower portion of the casing 100 and serves to bear an expansion pressure of the thermally expandable material that expands. Furthermore, the guide 300 provides a movement path to the piston 400 that reciprocates in response to expansion and contraction of the thermally expandable material, that is, the guide 300 guides the piston 400.

Herein, the guide 300 has a cylindrical seal cap 310 mounted to a lower end thereof. The seal cap 310 is constructed from an elastic material which is preferably a rubber material and more preferably an oil-resistant rubber which is a hydrogenated acrylonitrile-butadiene rubber (H-NBR) produced by emulsion polymerization, and prevents foreign substances accumulated on the bottom of the guide cap 600 from penetrating between the guide 300 and the piston 400. In other words, the seal cap 310 prevents a phenomenon where the piston 400 cannot be moved upward along the guide 300 due to the foreign substances present between the guide 300 and the piston 400, that is, the seal cap 310 prevents a phenomenon where the piston 400 stops moving in a state where the valve 700 is opened.

FIG. 2A is a view showing the seal cap 310 and FIG. 2B is a sectional view showing the seal cap 310. As shown in FIG. 2B, the seal cap 310 includes a sealing portion 311 and a coupling portion 312.

The sealing portion 311 is in surface contact with an outer peripheral surface of the piston 400 to prevent foreign substances from penetrating into a path defined between an inner peripheral surface of the guide 300 and the outer peripheral surface of the piston 400.

The coupling portion 312 has a groove structure 312 a centrally formed on an inner peripheral surface thereof as a coupling structure to be coupled to the lower end of the guide 300. The groove structure 312 a is engaged with a protrusion 301 of the guide 300 corresponding thereto as shown in FIGS. 3A and 3B. Herein, the groove structure 312 a is configured such that an inner diameter thereof gradually increases upward. FIG. 2B is the sectional view in which the upper and lower sides of the guide 300 are reversed and thus shows that the inner diameter of the groove structure 312 a gradually increases downward.

Furthermore, the piston 400 is provided to be movable upward and downward along the inner peripheral surface of the guide 300 and reciprocates in response to expansion and contraction of the thermally expandable material in the casing 100. Herein, the piston 400 reciprocates by receiving through a transfer fluid and the like, a deformation force exerted thereon by the sealing member 500, the sealing member being deformed in response to the expansion of the thermally expandable material.

Meanwhile, the sealing member 500 is provided at a lower end portion of the casing 100 to seal the thermally expandable material in the casing and is deformed in response to expansion and contraction of the thermally expandable material. Herein, if the sealing member 500 is a diaphragm, the sealing member is constructed from a material that is capable of being deformed and then restored to an original shape thereof in response to the expansion pressure of the thermally expandable material, the sealing member having a thin plate shape to be secured to the lower end portion of the casing 100. Meanwhile, the sealing member 500 may be a cap-shaped rubber sleeve, but is not limited thereto.

Furthermore, the guide cap 600 is provided to be movable upward and downward on a passage of the coolant along the outer peripheral surface of the guide 300 due to a pressing force exerted thereon by the piston 400. In other words, the guide cap 600 reciprocates on the passage of a thermostat housing 1300 by using the expansion pressure of the thermally expandable material heated by the heater 200, and such a reciprocating motion is achieved through cooperation between the guide 300, the piston 400, and the sealing member 500. Herein, the guide cap 600 has a discharge hole 610 formed at a lower portion thereof and through which foreign substances are discharged. Meanwhile, the guide cap 600 has a ring-shaped member 620 provided between the guide cap 600 and the guide 300 to block foreign substances flowing into the guide cap 600 from thereabove while preventing hot water flowing through the discharge hole 610 from being discharged to an upper portion of the guide cap 600.

FIG. 4A is a view showing the guide cap 600 and FIG. 4B is a sectional view showing the guide cap 600. As shown in FIGS. 4A and 4B, the guide cap 600 has the through hole 610 through which foreign substances accumulated on the bottom of the guide cap 600 are discharged.

Herein, one discharge hole 610 may be formed as shown in FIGS. 1 and 4A, but two discharge holes 611 and 612 may be formed as shown in FIG. 4B. The position and the number thereof are not limited.

Furthermore, as shown in FIG. 4B, the guide cap 600 may have a groove 621 horizontally formed along an upper portion of an inner upper peripheral surface thereof such that the ring-shaped member 620 provided between the guide cap 600 and the guide 300 is inserted into the groove 621.

Herein, the ring-shaped member 620 may have an 0-ring shape as shown in FIG. 1, but may have various shapes such as an X-ring shape, an E-ring shape, and the like as long as the ring-shaped member 620 serves to block inflow of foreign substances.

Meanwhile, the valve 700 is coupled to the guide cap 600 to open and close the passage of the coolant. In other words, the guide cap 600 is provided in conjunction with the guide 300 to control the flow of a coolant supplied to the thermostat housing 1300 in accordance with linear movement of the piston 400 provided in the guide 300, while the valve 700 is provided at an upper end that extends from an outer peripheral surface of the guide cap 600. As shown in FIG. 1, the valve 700 may be connected to the guide cap 600 by a valve guide 710 that supports the guide cap 600, but is not limited thereto.

FIG. 5 is a vertical sectional view showing an opened state of a valve of the electronic thermostat according to the embodiment of the present invention. The operation of the electronic thermostat according to the present invention will now be described with reference to FIGS. 1 to 5.

First, FIG. 1 shows a state before the thermally expandable material in the casing 100 expands and the valve 700 closes the passage of the thermostat housing 1300 and thus does not permit the flow of the coolant.

Thereafter, when the temperature of an engine increases, the external power source is applied to the lead wires 210 through the connector 1100. Herein, when an electric current supplied from the external power source flows through the lead wires 210, the coil provided in the heater 200 generates heat.

Thereafter, when the heater 200 heats the thermally expandable material in the casing 100 with heat of the coil, the thermally expandable material expands to cause the sealing member 500, for example, the diaphragm or sleeve, to be deformed in response to the expansion pressure of the thermally expandable material, causing the piston 400 to be moved downward by the transfer fluid, etc.

Herein, the piston 400 is moved downward along the inner peripheral surface of the guide 300, causing the guide cap 600 to be pushed downward. This causes the valve 700 coupled to the guide cap 600 to be moved downward in conjunction therewith and thus to open the passage of the thermostat housing 1300.

Thus, as shown in FIG. 5, the coolant flows in a predetermined direction A, permitting foreign substances carried through the coolant, such as sand generated during the engine injection molding process, foundry sand, sludge formed due to mixture of the coolant and water, and the like, to flow into the guide cap 600. Herein, the foreign substances are enabled to be discharged externally through the discharge hole 610 formed at the lower portion of the guide cap 600 without being accumulated. In other words, when the foreign substances are accumulated on the bottom of the guide cap 600, the piston 400 cannot be moved downward by a height at which the foreign substances are accumulated and thus the valve 700 cannot be closed. However, the electronic thermostat according to the present invention can prevent the foreign substances from accumulating, resulting in the valve 700 being constantly accurately opened and closed during long-term use of the thermostat.

Furthermore, the ring-shaped member 620 provided between the guide cap 600 and the guide 300 prevents hot water that may flow in through the discharge hole 610 formed at the lower portion of the guide cap 600 from being mixed with the coolant. Additionally, the ring-shaped member 620 provided between the guide cap 600 and the guide 300 reduces the amount of foreign substances flowing into the guide cap 600.

Meanwhile, even when foreign substances are slightly accumulated on the bottom of the guide cap 600, the seal cap 310 prevents the foreign substances from penetrating between the inner peripheral surface of the guide 300 and the outer peripheral surface of the piston 400 and stopping movement of the piston 400.

According to the electronic thermostat according the present invention described above, it is possible to prevent failure where the valve is not closed due to accumulation of foreign substances, preventing emission standards from becoming unsatisfactory, a reduction in fuel mileage, inoperative heating, an increase in pressure of coolant and mission oil systems, and the like from occurring due to inflow of the coolant upon valve opening.

Although the disclosed method and apparatus have been described with reference to the embodiments shown in the drawings for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. It is thus well known to those skilled in that art that the present invention is not limited to the embodiment disclosed in the detailed description, and the patent right of the present invention should be defined by the scope and spirit of the invention as disclosed in the accompanying claims. 

What is claimed is:
 1. An electronic thermostat configured to control flow of a coolant by using a piston reciprocating in response to expansion and contraction of a thermally expandable material, the electronic thermostat comprising: a casing having a space defined therein to accommodate the thermally expandable material; a heater inserted into the thermally expandable material filled in the space of the casing and generating heat upon application of an external power source; a guide provided at a lower portion of the casing and bearing an expansion pressure of the thermally expandable material that expands; the piston provided to be movable upward and downward along an inner peripheral surface of the guide; a sealing member provided at a lower end portion of the casing and sealing the thermally expandable material in the casing; a guide cap provided to be movable upward and downward on a passage of the coolant along an outer peripheral surface of the guide by a pressing force exerted thereon by the piston; and a valve coupled to the guide cap to open and close the passage, wherein the guide cap has a discharge hole formed at a lower end thereof.
 2. The electronic thermostat of claim 1, further comprising: a ring-shaped member provided between the guide cap and the guide.
 3. The electronic thermostat of claim 2, wherein the guide has a cylindrical seal cap mounted to a lower end thereof.
 4. The electronic thermostat of claim 3, wherein the seal cap includes: a sealing portion being in surface contact with an outer peripheral surface of the piston; and a coupling portion coupled to the lower end of the guide, wherein the coupling portion has a groove structure centrally formed on an inner peripheral surface of the seal cap, and the guide has a protrusion formed at the lower end thereof to correspond to the groove structure.
 5. The electronic thermostat of claim 4, wherein the groove structure and the protrusion are configured such that an inner diameter and an outer diameter thereof increase upward, respectively. 